This invention relates to a membrane separation device. More particularly, it relates to a means for attaching an end cap to the tubesheet of a hollow fiber membrane separation module or a means for attaching the tubesheet of one hollow fiber module to the tubesheet of another hollow fiber module. In another aspect, this invention relates to a membrane separation device comprising a hollow fiber membrane bundle and tubesheets, end caps, clamshell retainer means, circumferential keeper means, and optionally a hollow envelope enclosing the membrane separation module. This invention also relates to a method of separating gas compositions using such a membrane separation device.
Hollow fiber membrane separation modules generally consist of a hollow fiber membrane bundle formed from a plurality of hollow fiber membranes arranged about a core or mandrel and held together in place by tubesheets. The modules typically are enclosed in a pressure vessel having a cylindrical tube and end caps which contains all the components of the module. End caps of appropriate dimensions and with appropriate fluid connection ports are typically threaded into or onto the cylindrical tube portion of the pressure vessel. Alternatively, the cylindrical tube portion of the pressure vessel may be flanged in such a fashion so as to mate with a similarly flanged end cap bolted or screwed thereto. The pressure vessel supports the module, protects module components, defines fluid flow regions in conjunction with other module components, and protects operators from possible failure of module components. Conventional pressure vessels usually add a significant amount to the cost of membrane devices since such vessels must be large enough to accommodate the entire module and strong enough to withstand the pressures commonly employed. Such pressure vessels are also generally machined to close tolerances from high strength and corrosion resistant materials.
What is needed is a means of attaching an end cap to the tubesheet of a hollow fiber membrane module, or for attaching the tubesheet of one hollow fiber membrane module to the tubesheet of another hollow fiber membrane module, which is efficiently and easily assembled, without the aid of special tools. What is further needed is a more cost effective means of housing a hollow fiber membrane separation module. What is also needed is an assembled device which is more compact and less bulky and weighs less than conventional devices.